Stratification week 9

First intermediate layer forms

After the periderm forms and begins to differentiate, the underlying single layer of presumptive basal keratinocytes is fairly stable until the time of embryonic-fetal transition at the end of week 8 of gestation. At this point the presumptive keratinocytes divide, and give rise to daughter cells which move up to form the first intermediate layer (the layer between the basal cells and the periderm).

Four and more cell layers

One or two more layers of intermediate cells are added to the epidermis during the fourth and fifth months of gestation.

Note the 4-5 layers of stratified, differentiated keratinocytes overlaying a cellular dermis.